A comparison of step‐, pressure‐, and continuous‐wire‐gage wave recordings in the Golden Gate Channel

Abstract

Step‐, pressure‐, and continuous‐wire‐typewave gages were installed on a steel pile located in 35 to 40 ft of water approximately 600 ft off the northeastern end of Baker's Beach, San Francisco. Simultaneous measurements with all gages were made on a nearly continuous basis during most of April, 1953. These data have been evaluated to obtain characteristic wave periods and heights, height probability distributions, autocorrelation functions, and power spectra. In addition, direct recordings of wave slopes were made possible by using a three‐wire continuous‐wire gage, and a brief description is given of certain of the characteristics of these data. While the frequency responses of all three instruments were nearly identical, surface waves derived from the subsurface pressure‐gage recordings were shown to underestimate true values by an average factor of about 25 pct. The rather complex oceanographic structure of the channel is emphasized by occasional well‐marked surges having periods of about three minutes with heights up to one foot and by significant changes occurring in the characteristic wave period.